How Life Started

Early Earth

membrane-bound proto-cells living cells self-replicating system enclosed in a selectively permeable, protective lipid sphere DNA RNA enzymes and other proteins formation of protein-RNA systems, evolution of DNA lipid spheres spontaneous formation of lipids, carbohydrates, amino acids, proteins, nucleotides under abiotic conditions

electrodes to vacuum pump spark discharge CH4 NH3 H2O H2 gases water out condenser water in water droplets water containing organic compounds boiling water liquid water in trap

Figure 14.4(1) Page 224 Do not post to Internet

Archaebacterial Lineage Ancestors of Eukaryotes Noncyclic pathway of photosynthesis Origin of Prokaryotes Cyclic pathway of photosynthesis Eubacterial Lineage Aerobic respiration 3.8 3.2 2.5 billion years ago

origin of mitosis, meiosis ARCHAEBACTERIA Extreme halophiles Methanogens Extreme thermophiles origins of animals EUKARYOTES Animals origins of eukaryotes origins of fungi Fungi Heterotrophic protistans origin of mitosis, meiosis Photosynthetic protistans Photosynthetic protistans endosymbiotic origins of mitochondria Plants origins of plants endosymbiotic origins of chloroplasts EUBACTERIA Oxygen-producing photosynthetic eubacteria Other photosynthetic eubacteria Heterotrophic and chemoautotrophic eubacteria 1.2 billion years ago 900 million years ago 435 million years ago

cytoplasm with ribosomes DNA in nucleoid pilus bacterial flagellum outer capsule cell wall plasma membrane

coccus bacillus spirillum

Bacterium before DNA replication DNA replication begins DNA replication completed

cell-wall material deposited Membrane growth moves DNA molecules apart New membrane and cell-wall material deposited Cytoplasm divided in two Stepped Art

molecular origin of life to ancestors of eukaryotes EUBACTERIA ARCHAEBACTERIA spirochetes extreme halophiles methanogens Gram-positive bacteria chlamydias cyanobacteria proteobacteria extreme thermophiles molecular origin of life

Representative habitat for methanogens Do not post to Internet

Representative habitat for extreme thermophiles Do not post to Internet

Representative habitat for extreme halophiles Do not post to Internet

Figure 14.8d Page 228 Do not post to Internet

Figure 14.10b Page 229 Do not post to Internet

Figure 14.11 Page 229 Spirochete that causes Lyme disease Deer ticks Typical rash Do not post to Internet

Endospore developing inside a cell of Clostridium tetani Figure 14.12 Page 230 spore coat Endospore developing inside a cell of Clostridium tetani Do not post to Internet

In-text Figure Page 230 Berkeley Pit Lake Do not post to Internet

Figure 14.13 Page 231 ? branch leading to plants branch leading to fungi branch leading to animals charophytes green algae Stramenopiles amoeboid protozoans Alveolates brown algae red algae ciliates chrysophytes sporozoans oomycotes ? dinoflagellates “crown” of eukaryotes (rapid divergences) slime molds euglenoids kinetoplastids (e.g., Trypanosoma) parabasalids (e.g., Trichomonas) diplomonads (e.g., Giardia) endosymbiotic origins from prokaryotic ancestors

Influenza virus A herpes virus Do not post to Internet

viral protein lipid envelope (derived from host) viral coat (proteins) viral RNA reverse transcriptase enveloped virus (HIV)

DNA protein coat complex virus sheath base plate tail fiber

viral RNA protein subunits of coat polyhedral virus helical virus

Lysis of host cell is induced; infectious particles escape. Lytic Pathway Tail fibers and other parts are added to coats. Virus particles bind to wall of suitable host. Viral genetic material enters cell cytoplasm. Viral protein molecules are assembled into coats; DNA is packaged inside. Viral DNA directs host machinery to produce viral proteins and viral DNA.

Viral DNA usually becomes integrated into the bacterial chromosome. Lysogenic Pathway Viral DNA is excised from chromosome and cell enters lytic pathway. Prior to prokaryotic fission, the chromosome and integrated viral DNA are replicated. After binary fission, each daughter cell will have recombinant DNA.

* Includes pneumonia, influenza, and whooping cough. ** Includes amoebic dysentery, cryptosporidiosis, and gastroenteritis. 500,000 1 million Bacteria Tetanus 200 million Virus Hepatitis B Viruses Measles 2.6 million 5.6 million Virus (HIV) AIDS 2.5–2.7 million 110 million Sporozoans Malaria 3.1 million 9 million Tuberculosis 1.8 billion Bacteria, viruses, protozoans Diarrhea** 4.7 million 1 billion Bacteria, viruses Acute respiratory infection* Disease Estimated Deaths per Year Estimated New Cases per Year Main Agents Table 14.1  The Eight Deadliest Infectious Diseases Table 14.1 Page 245

HIV, agent of AIDS Agent of SARS Do not post to Internet